1. Field of the Invention
The technical field of the disclosed invention relates to a semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
There are a wide variety of metal oxides and such metal oxides are used for various applications. Indium oxide is a well-known material and is used as a transparent electrode material which is necessary for liquid crystal displays and the like.
Some metal oxides have semiconductor characteristics. The examples of such metal oxides having semiconductor characteristics are, for example, tungsten oxide, tin oxide, indium oxide, zinc oxide, and the like. A thin film transistor in which a channel formation region is formed using such metal oxides is already known (for example, see Patent Documents 1 to 4, Non-Patent Document 1, and the like).
As metal oxides, not only single-component oxides but also multi-component oxides are known. For example, InGaO3(ZnO)m (m: natural number) having a homologous phase is known as a multi-component oxide semiconductor including In, Ga, and Zn (for example, see Non-Patent Documents 2 to 4 and the like).
Furthermore, it is confirmed that an oxide semiconductor including such an In—Ga—Zn-based oxide is applicable to a channel formation region of a thin film transistor (for example, see Patent Document 5, Non-Patent Documents 5 and 6, and the like).